The present invention relates to a cooling jacket for transmitting heat-generation into a liquid refrigerant or coolant flowing within an inside thereof, and in particular, it relates to a cooling jacket to be used within a liquid cooling system, for enabling effective cooling of a heat-generating element, within various kinds of electronic apparatuses mounting the said heat-generating element therein, i.e., a semiconductor integrated circuit element, within an inside thereof, such as, a desk-top type personal computer and a server, and further a notebook-type personal computer, etc.
Conventionally, each of the electronic apparatuses, such as, the desk-top type personal computer and the server, and further the notebook-type personal computer, comprises the semiconductor element, as being the heat-generating element, such as, a CPU (Central Processing Unit), representatively, and for this reason, in general, it necessitates cooing for maintaining a normal operation of the said heat-generating element. Conventionally, for achieving such the cooling is applied, in general, so-called a cooling system of air-cooling type, wherein a heat-transferring member, being formed with fins in one body and called by “heat sink”, is attached on the said heat-generating element, thermally connected therewith, while providing a fan for blowing a cooling air thereon.
However, in recent years, accompanying with the tendency of small-sizing and high-integration of the semiconductor integrated circuit element, as being the heat-generating element, and further with high performances thereof, heat-generation is increased in such the heat-generating element, and at the same time localization is also generated, in particular, relating to heat-generating portions thereof. For this reason, attentions are paid on a liquid cooling-type cooling system having high cooling efficiency, which applies water as the coolant thereof, for example, in the place of the conventional air-cooling type cooling system, and it is actually adopted.
As such liquid cooling-type cooling system having high cooling efficiency, to be applied in the electronic apparatus, as was mentioned above, as was already known by the following Patent Documents, etc., in general, a member, being so-called a “heat-receiving jacket” or “cooling jacket”, is mounted on the surface of the CPU, as being the heat-generation body, directly, while running a liquid coolant within a flow passage, which is formed within an inside of the heat-receiving jacket. Thus, the heat-generation from the CPU is transmitted into the coolant flowing within the above-mentioned jacket, and thereby cooling the heat-generation body at high efficiency. However, in such the cooling system of liquid cooling type, normally, a heat cycle is built up with using the cooling jacket mentioned above as a heat-receiving portion, and in more details thereof, it comprises a circulation pump for circulating the liquid coolant within the cycle, a radiator to be a heat radiation portion for radiating heat of the liquid coolant into an outside, and further a coolant tank provided in a part of the cycle, depending on the necessity thereof, for storing the liquid coolant therein, and wherein, those are connected through metal tubes or tubes made of an elastic body, such as, rubber, etc., for example.
Patent Document 1: Japanese Patent Laying-Open No. Hei 6-266474 (1994); and
Patent Document 2: Japanese Patent Laying-Open No. Hei 7-142886 (1995).
By the way, within the liquid cooling system of actively circulating the liquid coolant within the system, as was known by the conventional arts mentioned above, the cooling jacket for transmitting the heat from the heat-generation body into the liquid coolant, in general, has such the structures that the flow passage for the liquid coolant is formed within a housing made of a metal, such as, copper or aluminum, etc., or that a metal pipe is welded on a metal plate. However, in recent years, accompanying with an increase of heat value within the heat-generating element, in particular, it is strongly demanded to improve the cooling capacity thereof, and for example, with the radiator, an electromotive fan is further attached thereon, so as to accelerate the heat radiation, compulsively. However, it cannot be said necessarily that sufficient improvements are made, in relation to an improvement of the cooling jacket, in particular, the heat conduction thereof.
Thus, as is apparent from the mentioned above, within the cooling jacket of the conventional art, the liquid coolant cooled down in the radiator flows into the flow passage formed within the metal housing thereof. In that instance, on a base portion of the cooling jacket (i.e., a metal plate portion to be in contact with a surface of the heat-generating element), the heat generated from the LSI, for example, is transferred into the liquid coolant through diffusion thereof; however, with the cooling jacket having such the conventional structures, since the said base portion thereof has only wall portions a plural number thereof, which are formed on a metal plane plate, for enlarging an area of contacting with the liquid coolant, therefore the heat can diffuse into direction of the plane on the metal plate, but it has such the structure that the heat can hardly diffuse into the vertical direction (i.e., into the wall portions). Thus, with the cooling jacket of the conventional art, the heat cannot be transferred effectively from the wall portions to the liquid coolant, even if enlarging the area to be contacted with the liquid coolant by means of the wall portions, and therefore it has a large heat resistance. For this reason, there is pointed out a drawback that it is not always possible to obtain the sufficient cooling capacity with it.